A few of my favourites have to be...
My own of course, DigiCurve - Alpha...
Link
iCatcher Colour Touch 2...
Link
iCatcher Colour Touch...
Link
Original iCatcher...
Link
Greyt...
Link
HiPod (yes it looks like an iPod, but its very sleek
)...
Link
Its best just to go through the 24bit WPS thread and find one you like (album art ones start at about the end of page 6)...
H3xx Rockbox 24bit Color WPS here. No Discussion (56K Warning)
If you haven't yet read about where to put the album art, there is a guide here...
[HOW TO] Album Art Made Easy